Definition of "unpurchased"

There breathes no being but has some pretence / To that fine instinct called poetic sense; […] / The freeman, casting with unpurchased hand / The vote that shakes the turrets of the land.

1836, Oliver Wendell Holmes, Sr., “Poetry: A Metrical Essay”, republished in The Poems of Oliver Wendell Holmes, Boston, Mass.: Ticknor and Fields, 1862, OCLC 5091562, pages 7–8